Genomic imprinting is defined as the unequal expression of the maternal and paternal alleles of a gene. A variety of experimental approaches, including the classical nuclear transplantation studies of McGrath and Solter, have helped to establish that appropriate expression of imprinted genes is critical to mammalian development. The long term goals of this research are to use a mouse model to identify novel imprinted genes and to examine the functions of these genes during mouse and human development. We have previously devised a novel breeding strategy which exploits mouse strains that carry Robertsonian chromosomes to generate embryos that are uniparental disomic (UPD) for chromosome 7; in other words, both copies of this chromosome have been derived from either the mother or the father. We propose to continue the systematic analysis of this cross, the experimental aims am divided into four Sections. One, novel imprinted genes will be identified from UPD 7 mouse embryos using comparative RNA analysis (differential display). Two, resulting cDNAs will be mapped to confirm the location of the corresponding genes on chromosome 7, sequenced and evaluated for allele-specific expression. Three, the temporal and spatial expression patterns of identified genes will be examined by in situ hybridization using staged and sectioned mouse embryos. Four, the candidacy of the human counterparts of imprinted mouse genes as disease genes will be evaluated. It is anticipated that these studies will not only provide novel insight into the nature and role(s) of imprinting in mammalian development but will also increase our understanding of the important role that imprinting plays in human diseases such as Prader-Willi syndrome (PWS), Angelman syndrome (AS), Beckwith-Wiedemann syndrome (BWS) and non-cytogenetically defined microdeletion syndromes and UPD effects.